Caption: Tetrahydrogestrinone (often referred to as THG or The Clear) is an anabolic steroid developed by Patrick Arnold. It has affinity to the androgen receptor and the progesterone receptor, but not to the oestrogen receptor. The drug has been considered a designer drug, closely related to the banned anabolic steroids gestrinone and trenbolone, and was referred to as an unapproved new drug by the Food and Drug Administration (FDA) in 2003 before the subsequent scheduling of it in 2005.